oldnum7 wrote:First, I wish to allude to the intra-Mercurial planet Vulcan, the existence of which is more than hypothetical, although it would be very desirable to have this proved beyond a doubt. You are doubtless aware that the great French astronomer, Le Verrier, when occupied with an investigation into the theory of the orbit of Mercury, found that a certain error in the assumed motion of its perihelion could only be accounted for by supposing that the mass of Venus is at least one-tenth greater than it was assumed from the measurements taken, or that there exists some unknown planet or planets between Mercury and the Sun, by which a disturbing action is produced. Le Verrier, without offering an opinion upon these hypotheses, towards the end of 1859 communicated them to the scientific world.

The precession of the perihelion can be account for if one includes the concept of "coordinate time" in the calculation of motion. A couple of papers were published in Reciprocity on it, years ago.

There is also the possibility that Vulcan isn't a planet at all, but the remnants of a 2nd star that formed a binary system here in the past--a star that exploded into time, rather than into space (Larson's "B" component) and as such, would experience the "inverse density gradient" effect and appear very small and massive, what conventional astronomers call a "black hole". Such a companion star would exist in an elliptical orbit about the sun, and may actually enter the photosphere, making the "planet" disappear for a time.

The Varo annotations indicate that this "planet" is one of the Great Arks--a mothership. If that were the case, we'd probably see it floating around the solar system, not just inside the orbit of Mercury...

Mercury's Moon, 1974 wrote:Two days before the 29 March 1974 Mariner 10 flyby past Mercury, one instrument began registering bright emissions in the extreme UV that had "no right to be there". The next day it was gone. Three days later it reappeared, and the "object" appeared to detach itself from Mercury. The astronomers first thought they had seen a star. But they had seen it in two quite different directions, and every astronomer knew that these extreme UV wavelengths couldn't penetrate very far through the interstellar medium, suggesting that the object must be close. Did Mercury have a moon?

Neith, the Moon of Venus, 1672-1892 wrote:In 1672, Giovanni Domenico Cassini, one of the prominent astronomers of the time, noticed a small companion close to Venus. Did Venus have a satellite? Cassini decided not to announce his observation, but 14 years later, in 1686, he saw the object again, and then entered it in his journal. The object was estimated to have about 1/4 the diameter of Venus, and it showed the same phase as Venus. Later, the object was seen by other astronomers as well: by James Short in 1740, Andreas Mayer in 1759, J. L. Lagrange in 1761 (Lagrange announced that the orbital plane of the satellite was perpendicular to the ecliptic). During 1761 the object was seen a total of 18 times by five observers. The observations of Scheuten on June 6 1761 was especially interesting: he saw Venus in transit across the Sun's disk, accompanied by a smaller dark spot on one side, which followed Venus in its transit. However, Samuel Dunn at Chelsea, England, who also watched that transit, did not see that additional spot. In 1764 there were 8 observations by two observers. Other observers tried to see the satellite but failed to find it.

The Earth's Second Moon, 1846-present wrote:In 1846, Frederic Petit, director of the observatory of Toulouse, stated that a second moon of the Earth had been discovered. It had been seen by two observers, Lebon and Dassier, at Toulouse and by a third, Lariviere, at Artenac, during the early evening of March 21 1846. Petit found that the orbit was elliptical, with a period of 2 hours 44 minutes 59 seconds, an apogee at 3570 km above the Earth's surface and perigee at just 11.4 km (!) above the Earth's surface. Le Verrier, who was in the audience, grumbled that one needed to take air resistance into account, something nobody could do at that time. Petit became obsessed with this idea of a second moon, and 15 years later announced that he had made calculations about a small moon of Earth which caused some then-unexplained peculiarities in the motion of our main Moon.

The list goes on and on... a rogue planet that seems to wander around the solar system, taking up orbit around the other planets, and sometimes even landing and taking off from the surface.